The comments follow Trump's visit to the state today where he tried on a face shield and brought his own mask — but refused to wear it in public during his Ford factory tour.

Before he arrived at the Michigan plant on Thursday, Nessel asked Trump to abide by Governor Whitmer and Ford's policy on face coverings in an open letter.

Trump briefly posed with a protective face shield that was handed to him during a tour at the Ford Rawsonville Components PlantCredit: Reuters

The president held a mask in his handCredit: Reuters

Trump holds the POTUS-emblazoned mask in his hands during the tourCredit: Reuters

But Trump appeared to ignore their pleas after he touched down at Detroit International Airport this afternoon and headed over to the Ford Rawsonville Components Plant in Ypsilanti.

Nessel has since blasted the president as a "petulant child" for refusing to wear one and declared he's no longer welcome in Michigan, reports say.

Upon arrival, he participated in roundtable with African American leaders at the Ford factory before briefly posing with a protective face shield that was handed to him during the tour.

Trump was pictured admiring the personal protective equipment being produced there and posed for the cameras briefly wearing a robust face shield.

"I didn't want to give the press the pleasure of seeing it," Trump said before showing off his own fabric face covering, which he'd reportedly removed for the duration of the tour.

"It was very nice. It looked very nice. They said [it was] not necessary."

Despite not wearing a mask for public parts of the tour - in breach of local rules - Trump was seen wearing his presidential seal mask in other parts of his tour.

Ford Motor Company CEO Jim Hackett (L) and Executive Chairman of Ford William Clay Ford Jr. (C) tour with US Trump at the Ford Rawsonville Plant todayCredit: AFP or licensors

Whitmer has asked that people wear masks in public placesCredit: AP:Associated Press

Trump's Michigan supporters took to the streets without masksCredit: Reuters

Ford Motor Company CEO Jim Hackett and Executive Chairman of Ford William Clay Ford Jr. both wore face coverings in the factory, which was repurposed to make ventilators for COVID-19 patients and other medical supplies.

Whitmer and Nessel had appealed to the president to wear a face mask to mitigate the spread of the deadly bug at the facility.

"While my Department will not act to prevent you from touring Ford's plant, I ask that while you are on your tour you respect the great efforts of the men and women at Ford - and across this state - by wearing a facial covering," wrote Nessel.

Trump left Washington earlier for Michigan at the Joint Base Andrews in MarylandCredit: Reuters

Jared Kushner looks on as US President Donald Trump pariticpates in a roundtable with African American leaders at the Ford factory todayCredit: AFP or licensors

"It is not just the policy of Ford, by virtue of the Governor's Executive Orders. It is currently the law of this State.

"Anyone who has potentially been recently exposed, including the President of the United States, has not only a legal responsibility, but also a social and moral responsibility, to take reasonable precautions to prevent further spread of the virus."

Ahead of Trump's visit, Ford Motor Co. reiterated its face mask policy to the White House earlier this week.

Ford told the Washington Post it requires everyone in factories to wear PPE, including masks, and that policy had been shared with the West Wing.

Trump has remained coy about whether or not he would wear a face covering, telling reporters that "in certain areas, I would. In certain areas, I don't."

Nessel said Trump was a 'petulant child'Credit: AP:Associated Press

The president toured the plant without a maskCredit: AFP or licensors

"But I will certainly look at it," he said. "It depends on what situation. Am I standing right next to everybody or am I spread out? Where it's appropriate, I would do it certainly."

Whitmer's coronavirus policy states that people should wear a face covering in confined public spaces.

On Wednesday, the president threatened to withhold funding from Michigan when it emerged mail-in voting would be permitted there this year to mitigate the spread of coronavirus at polling stations.